1. Field of the Invention
The present invention is related to a touch panel and a method of reducing noise coupled by a common voltage of a touch panel, and particularly to a touch panel and a method of reducing noise coupled by a common voltage of a touch panel that utilize a reverse circuit to reduce common voltage ripples of a liquid crystal panel coupled to a touch sensor.
2. Description of the Prior Art
Please refer to FIG. 1A and FIG. 1B. FIG. 1A is a diagram illustrating a touch sensor 102 outputting a sensing signal SS with higher signal-to-noise ratio when the touch sensor 102 is not coupled to a liquid crystal panel, and FIG. 1B is a diagram illustrating the touch sensor 102 outputting a sensing signal SS with lower signal-to-noise ratio when the touch sensor 102 is coupled to the liquid crystal panel 104. As shown in FIG. 1A, when sensing lines 1022 of the touch sensor 102 have voltage variation, capacitor variation, and/or electric field variation caused by an object 1024 (such as a finger), the touch sensor 102 outputs the sensing signal SS according to the voltage variation, the capacitor variation, and/or the electric field variation. Because the voltage variation, the capacitor variation, and/or the electric field variation of the sensing lines 1022 is only caused by the object 1024, the sensing signal SS outputted by the touch sensor 102 has the higher signal-to-noise ratio.
In addition, as shown in FIG. 1B, the voltage variation, the capacitor variation, and/or the electric field variation of the sensing lines 1022 is not only caused by the object 1024, but also influenced by common voltage ripples CV of the liquid crystal panel 104. Therefore, when the sensing lines 1022 of the touch sensor 102 have the voltage variation, the capacitor variation, and/or the electric field variation caused by the object 1024, the sensing signal SS outputted by the touch sensor 102 has the lower signal-to-noise ratio.